One relay has become known, for example, with the subject matter of EP 1 121 700 B2. This relay discloses a matching of the force-displacement characteristic to the drive characteristic in such a way that the actuator operates in two different actuation planes. That is to say, the actuator for the normally dosed contacts is in a different horizontal plane than, by comparison, the actuator for the normally open contacts. On movement of the actuator, the normally dosed contact opens first, before the normally open contact is dosed via an offset movement. This means that the force required by the actuation of the normally open contacts must be applied by the drive with delayed movement. This has the effect that the force-displacement characteristic of the contact set is modified. This provides the advantage that the drive characteristic and the contact-set characteristic are being matched to one another.
From the cited printed publication it follows that, in the normal state, the actuator is located, for example, at a certain point s1 (or to the right thereof) according to FIG. 7 of said printed publication, the point s1 being dependent on the degree of contact erosion. On attraction of the armature, the actuator moves to the left, with the force m of the magnet system initially increasing only slowly. However, in this region, up to a point s2, the actuating force required to overcome the normally-closed contact force (at the active normally-closed contact spring or at the anchor spring adapted thereto) is still relatively low as well, because of the large mechanical advantage.
From a point s2 to s3, a greater increasing restoring force is created by the added action of the active normally-open contact springs, which restoring force is overcome by a magnetic force m of the drive system that likewise increases more strongly in this region. From a point s3 to the mutual abutment of the contacts, both the restoring force f and the magnetic force increase substantially. This is the region of the overtravel, which continues to a point s4. The figures mentioned refer to FIG. 7 of EP 1 121 700 B2 and to FIG. 8 of the present invention, in which FIG. 7 of the cited printed publication has been plotted as prior art.
It is therefore the object of said printed publication to match the force-displacement characteristic or—as it is better termed in the description below, the contact-set characteristic, —to the discontinuous operating stroke (drive characteristic) of the magnet system.
In particular, the contact-set characteristic should not intersect with the drive characteristic of the magnet system, as this would result in unstable actuator travel, and speedy, smooth and continuous actuation of the contact set would no longer be ensured.
The printed publication cited solves this problem of the modification or modeling of the contact-set characteristic against a constant, consistent drive characteristic in such a way that the actuator acts on the contact set in two different planes.
In said printed publication, the points of contact engagement by the actuator on the associated contacts are dedicated and remain at a fixed, unchangeable distance from each other during the actuator travel. The mechanical advantage therefore is fixed. This means the distance between the point of fixation of each spring and the plane of actuation of this spring. A change-over from one plane of the points of application of force to another during the actuation does not take place. The height difference between the two actuation planes that are specified in the cited printed publication EP 1 121 700 B2, does not change.
It is characterizing for EP1 121 700 B2 that only a single actuation plane of the actuator is associated with each, the actuation of the normally closed contacts and the actuation of the normally open contacts, and therefore one contact type (normally closed or normally open) is assigned to each actuation plane. One distance, the distance between actuation plane 1 and the point of fixation of the spring, is associated with the normally open contact and the other distance, between actuation plane 2 and the point of fixation of the spring is associated with the normally closed contact.